Differential Psychology

differential psychology, branch of psychology that deals with individual and group differences in behaviour. Charles Darwin’s studies of the survival capabilities of different species and Sir Francis Galton’s researches on individual visual and auditory skills, as well as more recent experiments, have shown that both individual and group differences are quantitative rather than qualitative. Persons do not fall into sharply separated types, such as bright and dull, maladjusted and normal, introvert and extravert. On the contrary, in all psychological characteristics, individuals vary by degree along a continuous scale.